After the legislation was proposed several months ago, the Internal Market Bill attracted controversy from across the political spectrum in the UK, and has even caught the eye of the US president-elect Joe Biden.
A number of former Prime Ministers have all spoken out publicly against aspects of the bill, and the House of Lords has tried to force amendments on certain parts, although the government has said it will carry on trying to get the legislation through parliament as it is.
The government has said it will reinstate any parts of the Internal Market Bill legislation that are removed by the House of Lords.
The House of Lords will vote on the government’s highly controversial Brexit legislation this afternoon.
One of the most contentious aspects of the legislation relates to Northern Ireland, with some critics saying the bill would contravene the Good Friday Agreement, as well as the Withdrawal Agreement signed by Boris Johnson last year.
Speaking to Sky News, environment secretary George Eustice said: "The UK Internal Market Bill is not about undermining the Belfast Agreement, it's about standing behind it and making sure it works and looking after the interests of Northern Ireland - making sure the peace that has been hard-won there can carry on.
"The limited number of areas where we took a power, subject to parliament agreeing it, to be able to create legal clarity and legal certainty should there be areas that the Joint Committee process in our negotiations with the EU can't agree.”
He added: "We've got to provide that legal certainty and legal clarity and that's all the bill does."
What is the Internal Market Bill?
According to the government, the Internal Market Bill aims to allow goods and services to flow freely throughout the four nations of the United Kingdom.
Boris Johnson’s official spokesman said the Internal Market Bill will deliver a “vital legal safety net” which will allow the government to “take the necessary steps to ensure the integrity of the UK’s internal market”.
The bill aims to enshrine “mutual recognition and non-discrimination” in terms of trade between the four nations of the United Kingdom, making sure any goods and services which can be sold in one part of the UK can be sold in any other, and that no nation’s government can introduce regulations which would favour goods or services in one part of the UK over another.
So what’s the problem?
According to its critics, the main issue with the Internal Market Bill is that it would override parts of the withdrawal agreement, which was agreed by Boris Johnson last year as part of his “oven-ready Brexit deal”.
The bill would give ministers the power to make regulations relating to customs procedures for trade between Northern Ireland and Great Britain, as well as state aid.
It has also been reported that President-elect Joe Biden is concerned about the legislation, and its impact on the Good Friday Agreement, with the issue likely to be brought up when Mr Biden and Prime Minister Boris Johnson speak for the first time in the coming days.
It would also allow ministers to create regulations which would not be consistent with the UK’s obligations under the Withdrawal agreement.
Specifically, it will override parts of the Northern Ireland protocol, which recognises the issues in achieving frictionless trade across the UK as well as throughout the island of Ireland, in line with the Good Friday Agreement.
Ultimately it seeks to avoid a hard border between the Republic of Ireland, which will remain part of the EU single market, and Northern Ireland, which will fall under the UK’s internal market.
Does the bill break international law?
According to the government itself, yes.
Speaking in the commons, Northern Ireland Secretary Brandon Lewis told MPs that the Internal Market Bill breaks international law in a “specific and limited way”.
Firstly, the UK would be in breach of part of the Withdrawal Agreement by making it possible for ministers to create the regulations.
However, the real problems would occur if ministers actually exercised these powers, and in doing so actively breached the state aid and customs provisions of the Northern Ireland protocol.
Prior to an earlier vote, the European Union threatened legal action, and accused the UK of “seriously damaging” the trust between the two sides.
Ursulla Von-der Leyen, head of the EU Council, tweeted: "Very concerned about announcements from the British government on its intentions to breach the withdrawal agreement”.
Who voted for and against it?
Following the concession of a vote for MPs, the bill passed easily on Tuesday night (29 September).
After the first vote on the bill managed to pass despite a number of abstentions and two votes against by Conservative MPs, it seemed clear that the final commons vote would see the bill pass without much trouble.
There were no Tory rebels for the final commons vote, just the one abstention from former Prime Minister Theresa May.
The Conservative MPs who voted against the bill previously were Andrew Percy MP, of Brigg and Goole, and Sir Roger Gale, MP for North Thanet.
Who has spoken out against it?
Speaking at the dispatch box, Labour’s shadow business secretary Ed Miliband joked that Boris Johnson had been able to “unite all of his predecessors”, referring to the public interventions made by every living former PM warning against reopening the withdrawal agreement.
Theresa May, David Cameron, Gordon Brown, Tony Blair and John Major have all publicly weighed in on the Internal Market Bill, with David Cameron saying he has “misgivings” over the legislation.
Scottish First Minister Nicola Sturgeon described the Internal Market Bill as “a naked power grab which would cripple devolution”, saying it will lead to a “race to the bottom” on food standards.
What happens next?
The bill will now pass across to the House of Lords, where members can and are expected to frustrate the passing of the bill by tabling further amendments.
Once it has cleared the House of Lords, the bill will be put to Royal Ascent, before becoming law.